The present invention relates to packaging machines, and more particularly to a container forming device for use in packaging machines for making a web of packaging material into a tube, filling contents into the tube, transporting the tube a distance at a time which distance corresponds to the length of one container, sealing and cutting the tube transversely thereof to form a pillowlike uncompleted container, and eventually forming the uncompleted container into a rectangular parallelepipedal completed container, the container forming device being adapted to bond ears of the uncompleted container to required portions of the container body under pressure to eventually obtain the rectangular parallelepipedal completed container.
As disclosed, for example, in JP-A No. 10-29608 (1998), such forming devices are already known which comprise a container conveyor having a plurality of holders and intermittently drivable so as to halt the holders at an ear bonding station in succession, an upper ear pressing member disposed above the ear bonding station so as to be movable upward or downward for pressing upper ears against an upper wall of a container body, and a pair of lower ear pressing members arranged at opposite sides of the ear bonding station so as to be openable or closable for pressing lower ears against respective side walls of the container body, each of the holders comprising a bottom plate extending in parallel to a container transport path, and a side plate projecting upward from the bottom plate and extending orthogonal to the container transport path. The bottom plates of each pair of adjacent holders are adapted to place the container body thereon, with the side plates of the adjacent holders holding the container body therebetween. A pressure receiving member to be pressed on by the holder lower surfaces is disposed upwardly or downwardly movably so as not to permit upper ends of the side plates of the adjacent holders to move away from each other when the upper ear pressing member and the lower ear pressing members press the ears against the container body.
The conventional device described requires drive means for operating the pressure receiving member. This renders the device correspondingly more complex in construction and more costly to manufacture.
Further if used for larger containers, especially if the side plate has an increased height, the pressure receiving member is unable to receive the pressure of the upper ear pressing member and the lower ear pressing members to permit the holders to flex. It is then impossible to apply an appropriate pressure to the container, and the ears will not always be bonded to the container body properly.
An object of the present invention is to provide a container forming device wherein containers can be subjected to an appropriate pressure and which is free of the likelihood of permitting faulty bonding of the ears.
The present invention provides a container forming device comprising a container conveyor having a plurality of holders and intermittently drivable so as to halt the holders at an ear bonding station in succession, an upper ear pressing member disposed above the ear bonding station so as to be movable upward or downward for pressing upper ears against an upper wall of a container body, and a pair of lower ear pressing members arranged at opposite sides of the ear bonding station so as to be openable or closable for pressing lower ears against respective side walls of the container body, each of the holders comprising a bottom plate extending in parallel to a container transport path, and a side plate projecting upward from the bottom plate and extending orthogonal to the container transport path, the bottom plates of each pair of adjacent holders being adapted to place the container body thereon, with the side plates of the adjacent holders holding the container body therebetween. The container forming device is characterized in that the device comprises lock means for locking the side plates of the adjacent holders so as not to permit upper ends of the side plates to move away from each other when the upper ear pressing member and the lower ear pressing members press the ears against the container body.
With the container forming device of the invention, the pair of adjacent holders are locked directly by lock means to prevent the upper ends of the side plates of the adjacent holders from moving away from each other. This ensures the application of proper pressure to the container to eliminate faulty bonding of the ears.
The lock means has lock members movable upward and downward with the upper ear pressing member and engageable with the respective side plate upper ends of the adjacent holders from an upstream side of the container transport path and a downstream side thereof at the lower limit position of the downward movement thereof. The side plates of the adjacent holders can then be locked easily and reliably by the lock members to prevent the upper ends of the side plates from moving away from each other.
If each of the lock members has a vertical roller at a side plate engaging portion thereof, the lock members are smoothly engageable with the respective side plates without giving any impact.
The lower ear pressing members are attached respectively to lower ends of a pair of levers extending vertically, and a pair of connecting rods are connected, each at one end thereof, to the upper ends of the respective levers and have the other ends connected to a lift tube, the lock members being attached to the lift tube, the lift tube being movable upward and downward by drive means. This construction eliminates the need for a specific mechanism for moving the lock members upward or downward, rendering the lock members operable for locking by a simple mechanism.
The upper ear pressing member is attached to a lower end of a vertical lift rod fitted in the lift tube, and the lift rod has a shoulder portion formed approximately at a midportion of the height thereof by providing a small-diameter portion above the portion, the lift tube being provided with a cap at an upper end thereof, a compression coil spring being fitted around the small-diameter portion and provided between the shoulder portion and a top wall of the cap, the lift rod having an upper end extending through the cap top wall to project upward beyond the top wall, a stopper being provided at the upwardly projecting end of the lift rod. The compression of the spring then causes the upper ear pressing member to apply pressure to the upper wall of the container body. This makes it easy to determine the timing for the upper ear pressing member to press the container body upper wall and the timing with which the lower ear pressing members apply pressure to the container body side walls, with the holder side plates engaged by the lock members.